PROJECT SUMMARY Up to 50% of peripubertal youth with anxiety have unmet clinical needs, leaving these youth at high risk for suicide, depression and substance abuse across adolescence. In accord with the NIMH strategic plan, we aim to deepen mechanistic understanding of anxiety during the sensitive period of peripuberty to inform novel treatments and reduce health risks. This proposal focuses on negative overgeneralization, which is a core dimension of anxiety that is poorly understood, and refers to the tendency to generalize aversive responses from one context (house fire) to other contexts (camp-fire) that share features. Amygdala activity, induced by heightened emotional arousal, enhances plasticity in associative learning mechanisms, facilitating the binding of contextual features in memory that are only loosely related. We posit that sleep plays a critical role in negative overgeneralization. Specifically, we draw from basic neuroscience to propose a model by which heightened amygdala reactivity during wakefulness, induced by increased emotional arousal, facilitates replay of negative memories during sleep. This facilitated replay leads to the stabilization and integration (consolidation) of negative memories into long-term memory networks via slow wave oscillatory events during NREM sleep. We further propose that facilitated replay of negative memories during sleep promotes generalization by influencing underlying neurocomputational mechanisms (i.e., pattern completion ? a computational process that makes neural representations similar). Finally, we propose that sleep-dependent consolidation is malleable, such that Targeted Memory Reactivation (TMR) of positive memories during sleep can competitively displace consolidation of negative memories, and reduce negative overgeneralization. The current proposal tests this model using a novel multi-method approach combining neuroimaging, polysomnography, and a memory task that captures behavioral generalization and its underlying neural mechanisms (i.e. pattern completion). Aim 1 examines 200 peripubertal youth (ages 10-13 years) across a full continuum of anxious symptoms in a randomized sleep (n=140) versus wake (n=60) design to demonstrate sleep-dependent effects on behavioral and neural mechanisms of negative overgeneralization. Aim 2 focuses on the 140 youth in the sleep condition to evaluate amygdala reactivity at encoding and sleep neurophysiology during post-encoding sleep as mediators between anxiety and negative overgeneralization. Aim 3 uses the same design as the sleep condition but recruits a new sample of youth with elevated anxiety (n=60) to enroll in a randomized trial in which positive memories are cued during sleep (TMR, n=30), or sham cues are presented during sleep (n=30), to examine malleability of sleep-dependent mechanisms of negative overgeneralization. This project will set the stage for the long-term goal of developing novel interventions that manipulate sleep (e.g. via TMR) not only to improve existing symptoms, but also to positively shape neurodevelopment and reduce risk in the sensitive period of peripuberty.